Ssh-2.0-cisco-1.25 Vulnerability _best_
The string SSH-2.0-Cisco-1.25 is not a vulnerability itself, but rather the SSH banner (software version identifier) typically broadcast by Cisco IOS and IOS XE devices during the initial connection phase.
While the banner is a standard protocol feature, its presence allows attackers to perform reconnaissance to identify the device type and potentially target it with specific vulnerabilities. Common Vulnerabilities Associated with Cisco SSH
If your security scanner flagged this banner, it is likely checking for the following vulnerabilities that commonly affect Cisco SSH implementations: SSH Terrapin Prefix Truncation Weakness - Cisco Community
The string SSH-2.0-Cisco-1.25 is a software version banner identifying the Secure Shell (SSH) server implementation used by a wide variety of Cisco products, including Catalyst switches ISR routers ASA firewalls
While the banner itself is not a vulnerability, it indicates that the device is running a specific version of Cisco's proprietary SSH code. As of early 2026, this version has been linked to several critical security flaws, most notably a recent Unauthenticated Remote Code Execution (RCE) vulnerability. Vulnerability Overview: Unauthenticated RCE A major vulnerability (tracked as cisco-sa-erlang-otp-ssh-xyZZy
) was identified in certain Cisco products using this SSH implementation. Würth Phoenix
: Allows a remote, unauthenticated attacker to execute arbitrary commands with administrative privileges.
: A flaw in how the SSH server handles specific protocol messages during the cryptographic key exchange negotiation. Affected Products
: Multiple product lines, including those running specific versions of IOS XE and other platforms that integrate the affected Erlang/OTP SSH server components. Würth Phoenix Additional Associated Risks Devices reporting Cisco-1.25
may also be susceptible to other well-documented SSH weaknesses if not fully patched: SSH Terrapin Prefix Truncation Weakness - Cisco Community
Vulnerability Alert: SSH-2.0-Cisco-1.25
Overview
The SSH-2.0-Cisco-1.25 vulnerability is a security flaw in the Secure Shell (SSH) protocol implementation on certain Cisco devices. This vulnerability can allow an attacker to gain unauthorized access to the device, potentially leading to a compromise of the system's confidentiality, integrity, and availability.
Affected Devices
The vulnerability affects Cisco devices running SSH-2.0-Cisco-1.25, which is a specific implementation of the SSH protocol on Cisco IOS and IOS XE devices.
Vulnerability Details
The SSH-2.0-Cisco-1.25 vulnerability is caused by a weakness in the way the SSH protocol handles authentication requests. An attacker can exploit this vulnerability by sending a specially crafted SSH packet to the device, which can cause the device to crash or allow the attacker to gain unauthorized access.
Exploitation
An attacker can exploit this vulnerability using the following methods:
- Denial of Service (DoS): An attacker can send a malicious SSH packet to the device, causing it to crash or become unresponsive.
- Unauthorized Access: An attacker can use the vulnerability to gain unauthorized access to the device, potentially allowing them to execute arbitrary commands or access sensitive data.
Risk Level
The risk level of this vulnerability is considered High, as it can allow an attacker to gain unauthorized access to the device and potentially compromise the system's confidentiality, integrity, and availability. ssh-2.0-cisco-1.25 vulnerability
Mitigation and Remediation
To mitigate and remediate this vulnerability, Cisco has released patches and workarounds. The recommended solutions are:
- Upgrade to a patched version: Upgrade to a Cisco IOS or IOS XE version that is not vulnerable to this exploit.
- Disable SSH: Disable SSH on the device if it is not required.
- Implement additional security measures: Implement additional security measures, such as access control lists (ACLs) and intrusion prevention systems (IPS), to detect and prevent exploitation attempts.
Cisco Advisory
Cisco has released an advisory to address this vulnerability, which can be found at: https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20191106-ssh-1
References
Conclusion
The SSH-2.0-Cisco-1.25 vulnerability is a serious security flaw that can allow an attacker to gain unauthorized access to Cisco devices. It is essential to take immediate action to mitigate and remediate this vulnerability to prevent potential exploitation.
The string SSH-2.0-Cisco-1.25 is not a vulnerability itself, but rather the software version banner identifying a Cisco device's SSH service. Because this banner reveals the specific vendor and version, security scanners often flag it to suggest checking for known vulnerabilities associated with Cisco's SSH implementation.
The most critical contemporary vulnerability associated with Cisco SSH services is the Terrapin attack (CVE-2023-48795), which affects various Cisco platforms including Catalyst switches and XR routers. Key Vulnerabilities for Cisco SSH
While SSH-2.0-Cisco-1.25 identifies the service, the following actual vulnerabilities are often what scanners are warning about: Edit banner SSH-2.0-Cisco-1.25 The string SSH-2
Hello, Is possible to edit the default message SSH-2.0-Cisco-1.25 ?? ... Labels: NGFW Firewalls. Cisco Community
2. Detection methods
Part 7: Frequently Asked Questions
Q: Is ssh-2.0-cisco-1.25 a virus or malware?
A: No. It is a version banner. However, it indicates the device is likely missing security patches, making it a prime target for malware or ransomware.
Q: Can I hide the banner to pass a scan?
A: Yes, via ip ssh version and ip ssh server algorithm commands, plus changing the login banner. But this is "security by obscurity." A determined attacker will still probe for vulnerabilities.
Q: Does this affect Cisco Meraki or new Catalyst 9000 series?
A: No. Modern Cisco platforms run a completely different SSH stack (often based on OpenSSH) and report different version strings (e.g., SSH-2.0-Cisco-2.0 or SSH-2.0-OpenSSH_8.2).
Q: Is there a known exploit code available?
A: Yes. Public Metasploit modules and Python scripts exist for CVE-2009-2879 (DoS) and downgrade attacks. Always verify any exploit in a lab before testing on production.
2. Weak Cryptography (The "Legacy" Problem)
Legacy SSH implementations were designed in an era when cryptography standards were different. cisco-1.25 often supports:
- Weak Ciphers: It may default to or allow ciphers like Blowfish or Arcfour (RC4), which are now considered broken.
- Small Key Sizes: The RSA keys used by these older versions may be as small as 512 or 768 bits, which can be cracked by modern computing power relatively quickly.
- MD5/SHA1 Hashing: Older hashing algorithms are susceptible to collision attacks.
Introduction
In the world of network security, few things cause a spike in adrenaline quite like an unfamiliar banner appearing in your vulnerability scanner. For many system administrators and security analysts, the string "ssh-2.0-cisco-1.25" is one such trigger. Scrolling through a Nessus, OpenVAS, or Qualys report, this identifier often appears under "SSH Server Version Information," flagged with a medium or high-severity warning.
But is this a critical zero-day exploit? A backdoor? A misconfiguration?
The short answer is more nuanced. The "ssh-2.0-cisco-1.25 vulnerability" is not a singular, unpatched software flaw. Rather, it is a version fingerprint associated with specific Cisco operating systems (primarily older versions of Cisco IOS and Cisco NX-OS) that historically contained several known, documented vulnerabilities.
This article will dissect exactly what SSH-2.0-Cisco-1.25 means, explore the real vulnerabilities tied to this SSH implementation, distinguish between myth and fact, and provide a definitive guide to remediation. Denial of Service (DoS) : An attacker can
